(1) Field of the Invention
This invention relates to processes for producing chemically modified cellulosic fibers substantive to dyes of several major classes.
(2) Description of the Prior Art
Cellulosic fibers, as with other fiber types, vary greatly in their affinity and substantivity (i.e., requiring or involving no mordant) for various classes of dyes. Cotton and other cellulosics, such as viscose rayon, are readily dyed by azoic, direct, reactive, sulfur and vat dyes, but normally do not have affinity for acid or for disperse dyes. Therefore, it was necessary to chemically modify cellulose by covalent bond formation to make it substantive to various dye classes. However, this only altered the cellulosic fiber's substantivity for one class of dyes. Examples of this technique would inlcude: (a) preparation of chlorodeoxycellulose and its subsequent reaction with primary amines, which is a modification of cotton to render it substantive to acid dyes (Vigo, et al., U.S. Pat. No. 3,698,857; 1972); (b) formation of cellulose .beta.-mercaptethylaminocarboxylate and its subsequent reaction with methyl iodide to form an aliphatic sulfonium structure with improved affinity for direct dyes (M. Sakamoto, et al., J. Appl. Poly. Sci., 1973); and (c) benzoylation of cotton cellulose to make the fiber substantive to disperse dyes (Shikishima Spinning Co.,Jpn. Kokao Tokkyo Koho No. 80 80,579; (1980). One disadvantage noted in two of the three examples described above, would be, such changes in dye substantivity are usually achieved by multistep reactions with cellulose. Another disadvantage noted in these approaches is that these modified celluloses generally have inferior colorfastness to washing.